Congrats on your new house!
Tell mama that first of all, security bars need to be inside, not outside in order to really be effective. Not hard for a pro to cut right through that if it's on the outside.
Then, when on the inside, it needs to to be folding in order to pass a fire/emergency inspection as your window is an egress. A first responder may need to access your home per that window and precious minutes are lost.
I think it's lovely that your mom is concerned and old school. In the end, we found that bright sensor lights hung very high did the trick.
Here is a pic from our old cottage that we had years ago in NYC.